1. Field of Invention
The invention relates generally to medical devices for locating intravenous catheters and the like in a tissue mass. More particularly, the invention relates to an improved system including an insertion device/guard assembly and an intravenous catheter wherein means are provided for ensuring the enclosure of the pointed tip of the tissue piercing means of the insertion device prior to its withdrawal from the lumen of the catheter.
2. Summary of the Prior Art
Modern medical practice routinely includes the injection of medication hypodermically into patients, the positioning of catheters intravenously so as to provide feeding and/or medication introduction passageways through the outer tissue of a patient, and/or the withdrawal of various bodily fluids from patients. In each case, a sharp, unprotected, tissue piercing means such as a needle point is introduced into the caregiving environment. This occurs both (i) prior to the piercing of the patient's skin during the transfer of the needle from its original packaging to the patient, and (ii) subsequent to the withdrawal of the piercing means from the patient during the transfer of the needle to an appropriate disposal facility. The opportunities for the infliction an accidental nick or stick wound to the tissue of the caregiver or others, consequently, are equal to twice the number of tissue piercing procedures performed. It will be understood, therefore, that the accidental piercing of the skin of a health caregiver with any of the various tissue piercing devices commonly utilized by the medical profession is not an uncommon phenomenon. Indeed, it has been estimated that more that 2000 stick type wounds are sustained by health care workers in the United States each day.
A caregiver is subject to accidental needle sticks at all times during which an unenclosed needle point is present in the treatment environment. As a practical matter, this fact presents little danger to the caregiver at the initial stage of most medical procedures because the needle is usually sterile at that time. Once the needle has been placed in contact with the bodily fluids of a patient, however, an accidental needle stick may subject the caregiver to the transmission of serious, or even life threatening, illness. Chief among the diseases which may be communicated in this manner are hepatitis B and the human immunodeficiency virus (HIV). Hepatitis B is serious, but is not necessarily fatal. HIV, on the other hand, eventually causes acquired immune deficiency syndrome (AIDS) which is, so far as is presently known, invariably fatal. The danger arising from needle sticks with a contaminated needle, therefore, represents a severe health risk--a risk which both private institutions and governments worldwide are strenuously endeavoring to reduce.
In response to these health risks, numerous devices have been developed which attempt to remove the tip of a needle from the treatment environment after it has been contaminated by contact with possibly infected blood or other bodily fluids. Generally, these devices provide a member which is movable relative to the pointed end of the needle between a first, so-called "retracted", position wherein the point of the needle is exposed, and a second, so-called "guard", position wherein the point of the needle is effectively removed from the treatment environment. Specifically, in one prior device this has been accomplished by the movement of a shaft within the needle lumen from a retracted position wholly within the needle to a guarding position wherein the distal end of the shaft extends outwardly from within the pointed end of the needle (see, U.S. Pat. No. 4,828,547). Alternatively, an equivalent result has been achieved in other devices by moving a sleeve surrounding the needle shaft from a retracted position wherein the distal end of the sleeve is located proximally of the pointed tip of the needle to a guarding position wherein the distal end of the sleeve is located distally of and enclosing the pointed tip of the needle (see, for example, U.S. Pat. Nos. 4,778,453 and 4,631,056).
To date, the internal shaft alternative is the only one of these mechanisms which has permitted the pointed tip of the needle to be blunted prior to its removal from the tissue mass. Further, sleeves surrounding the needle typically have been provided having diameters substantially in excess of the needle diameter. In some cases this is because locking mechanisms associated with the needle shaft are located internally of the sleeve thereby requiring a large sleeve diameter relative to the needle diameter. In other cases, it has been determined that the danger to the health care worker is reduced by ensuring that the sleeve which must be manipulated by him/her in order to enclose the needle tip is large enough to be easily and securely grasped, yet small enough to prevent access to the needle point by the extremities of a caregiver.
The capability of blunting the needle point prior to its re-entry into the caregiving environment from a location within the body of a patient is very important. So long as the tip of a contaminated needle is exposed in the caregiving environment for any period of time, no matter how small, a finite possibility of the transmission of a fatal disease to a health caregiver is present. Nevertheless, the internal shaft alternative has been found to be excessively complex and expensive. In addition, there remains a finite chance of the infliction of a nick to a health care worker with the point of the needle in that alternative even after the blunting shaft has been deployed in its extended position. This is because in that configuration the point of the needle lies adjacent the outer surface of the blunting shaft such that the needle point remains exposed (albeit substantially flush against the blunting shaft).
Devices for the placement of intravenous catheters and the like in a tissue mass also are well known in the art. Typically, the catheter includes an elongated, hollow, flexible, tube having the smaller end of a generally funnel-shaped connecting fitting attached to one of its ends. The placement device includes a needle holder and a hollow needle. The needle has a pointed distal end and a proximal end connected by a shaft having a length slightly longer than the length of the flexible tube portion of the catheter. The needle holder generally includes a grasping portion and a neck portion. The neck portion surrounds and holds the proximal portion of the needle and has an exterior surface configured to mate with the generally funnel-shaped connecting fitting of the catheter. This configuration allows the fitting to be frictionally held on the neck of the needle holder when the catheter tube is telescoped onto the needle.
In use devices of this type are generally provided in a pre-assembled and presterilized condition such that (i) the catheter resides on the needle with the attachment fitting matingly engaging the neck portion of the needle holder and (ii) the pointed tip of the needle extends distally of the distal end of the catheter tube. The nurse or other caregiver simply takes the device from the package and, while grasping the handle portion of the needle holder, inserts the needle point into the tissue such that it enters a vein of the patient. The needle is then advanced into the vein so as to carry the distal end of the catheter tube (which rides in a close fit to the needle shaft) into the vein. Thereafter, the nurse grasps the attachment fitting on the proximal end of the catheter with one hand and the needle holder with the other hand, and withdraws the needle from the lumen of the catheter while holding the attachment fitting of the catheter stationary with respect to the tissue mass.
The needle then is discarded in a medically and environmentally accepted manner, and a desired source of medication and/or intravenous fluid is attached to the catheter's attachment fitting. In some instances, plastic sheaths are provided for the encasement of the needle prior its being discarded. In other cases, hospital policy may require the caregiver to clip the pointed end off of the shaft of the needle to prevent its subsequent use. As indicated above, however, no means are available whereby the tip of a tissue piercing needle is necessarily enclosed in the normal operation of the device prior to its withdrawal from the patient so as to assure the protection of health care workers from accidental stick wounds.